My children have never had lice until my youngest was 9. I tried several of the over the counter treatments however they were pricey and although they killed the lice there was some doubt that they were effectively killing nits. I was also concerned with the chemicals they contained. So I started to research for the best treatment. What I found was Vodka. Vodka contains ethanol which kills both lice and nits. I decided to use 4 oz of vodka mixed in a squirt bottle with 25 drops of tea tree oil (tea tree oil was shown to kill 100% of lice within 30 minutes of application) in a govt study. I also added 25 drops of lavender oil which was shown to kill nits when combined with tea tree oil. I used these in addition to the vodka just as insurance that I was covering all my bases. I soaked my daughters hair with the mixture put a shower cap on and had her sleep in it. In the morning I washed her hair with tea tree oil shampoo and then rinsed it with water then did an apple cider vinegar rinse. The apple cider vinegar actually dissolves the glue that holds the nit to the hair, for easy removal. I then put a tea tree oil conditioner and proceeded to comb her hair with a nit comb, section by section. Then I blow dryed the hair with high heat (heat also kills lice and nits). She went to school and didn't have a critter or egg on her.
I also took 6 oz of rubbing alcohol, with 25 drops each of tea tree oil, lavender, clove and eucalyptus oil and sprayed all my furniture, rugs, mattresses daily. I washed all our bedding, pillows clothing with hot water and 20 drops of tea tree oil in addition to laundry detergent. Dried all clothing on high heat. All bedding was washed daily to be on the safe side. When making our beds, the mattresses, pillows, sheets bedspreads were all sprayed daily with this alcohol/essential oil spray. I also made small spray bottles for us to take to work and school so we could spray our hair throughout the day as a precaution. Worked like a charm, cheap, not messy and safe.